A high temperature air heater including a heat transfer conduit located in higher temperature gas. The heat transfer conduit is made up of a heat transfer pipe through which the air to be heated flows and a refractory protective pipe covering the heat transfer pipe. A clearance is provided between the heat transfer pipe and the refractory protective pipe. The clearance makes it possible to accommodate the differences in thermal expansion between the heat transfer pipe and the refractory protective pipe to prevent damaging the refractory protective pipe, thus extending the service life of the high temperature air heater.